1. Field of Invention
This invention relates to brittle matrix composites and plant pulp, and especially to the processing and use of pulp fibers for reinforcing cement-based materials.
2. Description of the Prior Art
The concept of using fibers to improve the behavior of building materials is old; examples include adding straw fibers to sun-dried mud bricks (adobe) and asbestos fibers to pottery, thus creating a composite with a better performance. Such performance could be translated in the case of adobe by a better resistance to cracking and a better resistance to fragmentation after cracking induced by repetitive changes in temperature and humidity. It is no surprise that when Portland cement concrete started evolving as a building material, attempts were made to add fibers to it to improve its behavior. Early work in this area in the 19.sup.th century led to the development of ferrocement and reinforced concrete as known today. However, the use of continuous reinforcement required careful placement and higher labor technical skills, hence higher cost.
The idea of using strong discontinuous fibers as reinforcement for concrete has been a challenge to many civil engineers. Adding the reinforcement to the mixer in the form of fibers, simply like adding aggregates or admixtures, to create a homogeneous, isotropic, and moldable structural material is a dream that started more than a century ago, and is still in the making today. The fibers considered for the reinforcement of concrete include steel, polypropylene, nylon, glass, carbon, kevlar, and natural fibers. A selective number of patens in the field of cellulose fiber reinforced cement-based materials, which is the subject of this invention, is reviewed next. A listing of the references is first presented followed by a brief discussion of same.